A study will be made of the role of the mitochondrial ATPase, F1, in oxidative phosphorylation. The project will examine both catalysis and structure in the soluble enzyme and will attempt to relate critical features to the mechanism of action of the membrane-bound enzyme. Key areas of research will include a study of ATP synthesis by soluble F1, of the Pi binding site in the enzyme, its subunit localization and the relationship of the Pi site to adenine nucleotide binding sites on the molecule. An approach to the heterogeneity of the two major subunits of the enzyme will include isolation and analysis of individual peptides as well as a direct approach to the number of catalytic sites on the molecule.